user32: Add a test for ToUnicode - Win9x behaviour

[Andre Wisplinghoff]

Nikolay Sivov wrote:
> You should use dynamic linking here (GetProcAddress).
>
>
Is this necessary even though the function is there on 9x - returning 
unimplemented - as Paul wrote? I think you would need to do this if the 
function weren't there at all on some systems.

Best Regards
-- Andre Wisplinghoff